Clamping device and clamping system using the same

ABSTRACT

A central pillar ( 20 ) is projected upward from a reference block ( 1 ), and an inner sleeve ( 21 ) is fitted to an outer periphery of the central pillar ( 20 ) vertically movably. The inner sleeve ( 21 ) is pushed upward by a coned disc spring ( 25 ). An outer sleeve ( 31 ) to be inserted into a socket hole ( 3 ) of a movable block ( 2 ) makes a tapering engagement with the inner sleeve ( 21 ) from above. The inner sleeve ( 21 ) and the outer sleeve ( 31 ) are adapted to be diametrically expandable and contractible. An output member ( 36 ) is inserted into the central pillar ( 20 ), and an upper portion of the output member ( 36 ) is connected to the outer sleeve ( 31 ). A driving mechanism (D) in the reference block ( 1 ) moves the outer sleeve ( 31 ) downward for locking via the output member ( 36 ).

TECHNICAL FIELD

The present invention relates to a clamping apparatus for fixing amovable block such as a work pallet or a work to a reference block suchas a table of a machine tool, and furthermore, relates to a clampingsystem using the clamping apparatus.

BACKGROUND OF THE INVENTION

As such this clamping apparatus, one described in U.S. Pat. No.5,820,118 is conventionally available. According to this prior art, aplurality of rotatable clamps are arranged around a work placed on awork pallet, and a damper of each of the clamps is adapted to press thework from above.

The above-mentioned prior art contains such problems that, since aplurality of the clamps are arranged around the work, it is difficultmachining side surfaces of the work, in addition, it is impossible tomachine an upper surface of the work at pressed portions by theclampers.

It is an object of the present invention to provide a new clampingapparatus that makes it possible for the respective surfaces of amovable block such as a work or a work pallet to be easily accessed, andto provide a new clamping system using this clamping apparatus.

SUMMARY OF THE INVENTION

In order to accomplish the object mentioned above, the present inventionprovides the clamping apparatus as described below and as illustrated inFIG. 2A, FIG. 5A, FIG. 6 or FIG. 10 respectively for example.

An annular central pillar 20 is projected from a reference block 1toward a leading end, and an inner sleeve 21 is fitted onto the centralpillar 20 axially movably within a predetermined range. The inner sleeve21 is advanced toward the leading end by a predetermined advancingstroke by an advancing means 25. An outer sleeve 31 to be inserted intoa socket hole 3 of a movable block 2 makes a wedge engagement with theinner sleeve 21 from the leading end side. The outer sleeve 31 isadapted to be diametrically expandable and contractible. An outputmember 36 is inserted into a cylindrical hole 20 a of the annularcentral pillar 20 axially movably, and a leading end portion of theoutput member 36 is connected to the outer sleeve 31. A locking means 51and a releasing means 52 are provided in the reference block 1. Thelocking means 51 moves the outer sleeve 31 toward a base end for lockingvia the output member 36, while the releasing means 52 moves the outersleeve 31 toward the leading end for releasing via the output member 36.

The present invention functions as follows, for example, as shown inFIG. 2A.

In a released state shown in FIG. 2A, the releasing means 52 has movedthe outer sleeve 31 toward the leading end via the output member 36, andthe advancing means 25 has advanced the inner sleeve 21 toward theleading end by the predetermined advancing stroke.

To fix the movable block 2 to the reference block 1, the socket hole 3is fitted onto the outer sleeve 31, and thereafter, the locking means 51moves the output member 36 toward the base end for locking, and theouter sleeve 31 gradually makes a wedge engagement with the inner sleeve21.

Then, first, the outer sleeve 31 diametrically expands via the innersleeve 21 held at almost an advanced position by a pressing force of theadvancing means 25, by which the outer sleeve 31 comes into contact withthe socket hole 3. Next, the outer sleeve 31 diametrically expands whileforcing the advancing means 25 to retreat toward the base end via theinner sleeve 21, and the outer sleeve 31 comes into close contact withthe socket hole 3, and the outer sleeve 31 gradually forces the innersleeve 21 to retreat toward the base end against the pressing force ofthe advancing means 25. Subsequently, when the inner sleeve 21 retreatsby a dimension corresponding to the advancing stroke, the inner sleeve21 is directly or indirectly received by the reference block 1. Then,the outer sleeve 31 makes a strong wedge engagement with the innersleeve 21, which is received by the reference block 1, and the wedgeengagement makes the outer sleeve 31 expand diametrically, by which theouter sleeve 31 comes into strong and close contact with the socket hole3. Thereby, the output member 36 strongly presses a supported surface 2a of the movable block 2 toward a supporting surface 1 a of thereference block 1 via the outer sleeve 31, which is in the strong andclose contact state with the socket hole 3.

It is noted that, in the case where the supporting surface la of thereference block 1 and the supported surface 2 a of the movable block 2are in almost complete contact with each other at the beginning of thelocking movement and where the supported surface 2 a is received by thesupporting surface la, the outer sleeve 31 operates as follows duringthe locking movement.

After the outer sleeve 31 comes into close contact with the socket hole3, the outer sleeve 31 moves toward the base end while sliding on thesocket hole 3 of the movable block 2 received by the reference block 1.Then, as mentioned above, the inner sleeve 21 retreats by the dimensioncorresponding to the advancing stroke, and when the inner sleeve 21 isblocked from retreating, the outer sleeve 31 comes into strong and closecontact with the socket hole 3, and the outer sleeve 31 strongly pressesthe movable block 2 toward the reference block 1.

On the other hand, in the case where a gap remains between thesupporting surface 1 a of the reference block 1 and the supportedsurface 2 a of the movable block 2 at the beginning of the lockingmovement for some reason, the outer sleeve 31 operates as follows duringthe locking movement.

After the outer sleeve 31 comes into close contact with the socket hole3, the outer sleeve 31, which is in the close contact state with thesocket hole 3, moves the movable block 2 toward the reference block 1via the socket hole 3. Then, as mentioned above, the inner sleeve 21retreats by the dimension corresponding to the advancing stroke, andwhen the inner sleeve 21 is blocked from retreating, the outer sleeve 31comes into strong and close contact with the socket hole 3, and theouter sleeve 31 strongly presses the movable block 2 toward thereference block 1.

The present invention with the above-mentioned structure and functionprovides the following effects.

It becomes possible and easier to access five surfaces other than thesupported surface among six surfaces of the movable block. Therefore,for example, in the case where a work as the movable block is fixed tothe reference block, the five surfaces can be continuously machined byone clamping operation. In the case where a work pallet as the movableblock is fixed to the reference block, available area of the work palletis significantly increased.

It is noted that, in the present invention, it is preferable that aceiling portion of an inner space of the outer sleeve 31 is hermeticallycovered with a ceiling wall provided at the leading end portion of theoutput member 36. In this case, foreign matter such as swarf and cuttingoil can be prevented from entering the inner space of the outer sleeve31 by the ceiling wall, by which the clamping apparatus can be used fora long time without any maintenance.

In addition, in order to accomplish the object mentioned above, anotherinvention provides the clamping apparatus, for example, as describedbelow and illustrated in FIG. 7A.

In place of the outer sleeve 31, which is diametrically expandable andcontractible, an annular plug 71 to be inserted into the socket hole 3is arranged on an outer periphery of the inner sleeve 21. A plurality ofpressing members 72 are supported on a peripheral wall 71 a of theannular plug 71 radially movably and are arranged circumferentially atintervals. Each of the pressing members 72 makes a wedge engagement withthe inner sleeve 21 from the leading end side, and each of the pressingmembers 72 is adapted to be movable radially inward by a restoring means74. The leading end portion of the output member 36 is connected to theannular plug 71.

The another invention functions as follows, for example, as illustratedin FIG. 7A, in substantially the same manner as the foregoing invention.

In a released state shown in FIG. 7A, the releasing means 52 has movedboth the annular plug 71 and a plurality of the pressing members 72toward the leading end via the output member 36, and the advancing means25 has advanced the inner sleeve 21 toward the leading end by thepredetermined advancing stroke.

To fix the movable block 2 to the reference block 1, the socket hole 3is fitted onto both the annular plug 71 and a plurality of the pressingmembers 72, and thereafter, the locking means 51 moves the output member36 toward the base end for locking, and each of a plurality of thepressing members 72 gradually makes a wedge engagement with the innersleeve 21.

Then, first, each of the pressing members 72 moves radially outward viathe inner sleeve 21 held at almost the advanced position by the pressingforce of the advancing means 25, by which each of the pressing members72 comes into contact with the socket hole 3. Next, each of the pressingmembers 72 moves radially outward while forcing the advancing means 25to retreat toward the base end via the inner sleeve 21, and each of thepressing members 72 comes into close contact with the socket hole 3, andeach of the pressing members 72 gradually forces the inner sleeve 21 toretreat toward the base end against the pressing force of the advancingmeans 25. Subsequently, when the inner sleeve 21 retreats by thedimension corresponding to the advancing stroke, the inner sleeve 21 isdirectly or indirectly received by the reference block 1. Then, each ofthe pressing members 72 makes a strong wedge engagement with the innersleeve 21, which is received by the reference block 1, and each of thepressing members 72 moves radially outward, by which each of thepressing members 72 comes into strong and close contact with the sockethole 3. Thereby, the output member 36 strongly presses the supportedsurface 2 a of the movable block 2 toward the supporting surface la ofthe reference block 1 via the pressing members 72, which is in thestrong and close contact state with the socket hole 3.

It is noted that, in the case where the supporting surface 1 a of thereference block 1 and the supported surface 2 a of the movable block 2are in almost complete contact with each other at the beginning of thelocking movement and where the supported surface 2 a is received by thesupporting surface 1 a, the pressing members 72 operate as followsduring the locking movement.

After each of the pressing members 72 comes into close contact with thesocket hole 3, each of the pressing members 72 moves toward the base endwhile sliding on the socket hole 3 of the movable block 2 received bythe reference block 1. Then, as mentioned above, the inner sleeve 21retreats by the dimension corresponding to the advancing stroke, andwhen the inner sleeve 21 is blocked from retreating, each of thepressing members 72 comes into strong and close contact with the sockethole 3, and these pressing members 72 strongly press the movable block 2toward the reference block 1.

On the other hand, in the case where a gap remains between thesupporting surface la of the reference block 1 and the supported surface2 a of the movable block 2 at the beginning of the locking movement forsome reason, the pressing members 72 operate as follows during thelocking movement.

After each of the pressing members 72 comes into close contact with thesocket hole 3, the pressing members 72, which are in the close contactstate with the socket hole 3, move the movable block 2 toward thereference block 1 via the socket hole 3. Then, as mentioned above, theinner sleeve 21 retreats by the dimension corresponding to the advancingstroke, and when the inner sleeve 21 is blocked from retreating, each ofthe pressing members 72 comes into strong and close contact with thesocket hole 3, and these pressing members 72 strongly press the movableblock 2 toward the reference block 1.

The another invention with the above-mentioned structure and funtionprovides the following effects.

It becomes possible and easier to access five surfaces other than thesupported surface among six surfaces of the movable block. Therefore,for example, in the case where a work as the movable block is fixed tothe reference block, the five surfaces can be continuously machined byone clamping operation. In the case where a work pallet as the movableblock is fixed to the reference block, available area of the work palletis significantly increased.

It is noted that, in the another invention, it is preferable that aceiling portion of an inner space of the annular plug 71 is hermeticallycovered with the ceiling wall provided at the leading end portion of theoutput member 36. In this case, foreign matter such as swarf and cuttingoil can be prevented from entering the inner space of the annular plug71 by the ceiling wall, by which the clamping apparatus can be used fora long time without any maintenance.

Furthermore, in order to accomplish the object mentioned above, stillanother invention provides a clamping apparatus, for example, asdescribed below and illustrated in FIG. 2A, FIG. 7A, FIG. 11, FIG. 12A,FIG. 17A, FIG. 18A or FIG. 24, respectively.

An annular central pillar 20 is projected from a reference block 1toward a leading end, an inner engaging member 21 is arranged on anouter periphery of the central pillar 20. An outer engaging member (31,72) to be inserted into a socket hole 3 of a movable block 2 is adaptedto be diametrically expandable and contractible. The outer engagingmember (31, 72) makes a wedge engagement axially with the inner engagingmember 21, and the outer engaging member (31, 72), which is in the wedgeengaged state, is movable toward a base end and diametrically expandablefor locking. An output member 36 is inserted into the annular centralpillar 20 axially movably, and an output portion of the output member 36is connected to either the outer engaging member (31, 72) or the innerengaging member 21. An input portion of the output member 36 isconnectable to a driving means D.

It is noted that the driving means D can employ an automatic drivingmeans using an actuator such as a fluid pressure cylinder and anelectric motor, and can also employ a human-powered driving means.

The still another invention functions as follows, for example, asillustrated in FIG. 2A (or FIG. 7A), in substantially the same manner asthe foregoing inventions.

In the released state shown in FIG. 2A (or FIG. 7A), the driving means Dhas moved the output member 36 toward the leading end and the outerengaging member 31 (72) has moved toward the leading end whilecontracting diametrically.

To fix the movable block 2 to the reference block 1, the socket hole 3is fitted onto the outer engaging member 31, and thereafter, the drivingmeans D moves the output member 36 toward the base end, and the outerengaging member 31 gradually makes a wedge engagement with the innerengaging member 21.

Then, first, the outer engaging member 31 (72) diametrically expands viathe inner engaging member 21, by which the outer engaging member 31comes into close contact with the socket hole 3. Subsequently, when theouter engaging member 31 is blocked from moving toward the base end, theouter engaging member 31 makes a strong wedge engagement with the innerengaging member 21, and the outer engaging member 31 diametricallyexpands, by which the outer engaging member 31 comes into strong andclose contact with the socket hole 3. Thereby, the output member 36strongly presses the supported surface 2 a of the movable block 2 towardthe supporting surface la of the reference block 1 via the outerengaging member 31, which is in the strong and close contact state withthe socket hole 3.

It is noted that, in the case where the supporting surface 1 a of thereference block 1 and the supported surface 2 a of the movable block 2are in almost complete contact with each other at the beginning of thelocking movement and where the supported surface 2 a is received by thesupporting surface la, the outer engaging member 31 (72) operates asfollows during the locking movement.

After the outer engaging member 31 comes into close contact with thesocket hole 3, the outer engaging member 31 moves toward the base endwhile sliding on the socket hole 3 of the movable block 2 received bythe reference block 1. Then, as mentioned above, when the outer engagingmember 31 is blocked from moving toward the base end, the outer engagingmember 31 comes into strong and close contact with the socket hole 3,and the outer engaging member 31 strongly presses the movable block 2toward the reference block 1.

On the other hand, in the case where a gap remains between thesupporting surface 1 a of the reference block 1 and the supportedsurface 2 a of the movable block 2 at the beginning of the lockingmovement for some reason, the outer engaging member 31 (72) operates asfollows during the locking movement.

After the outer engaging member 31 comes into close contact with thesocket hole 3, the outer engaging member 31, which is in the closecontact state with the socket hole 3, moves the movable block 2 towardthe reference block 1 via the socket hole 3. Then, as mentioned above,when the outer engaging member 31 is blocked from moving toward the baseend, the outer engaging member 31 comes into strong and close contactwith the socket hole 3 and the outer engaging member 31 strongly pressesthe movable block 2 toward the reference block 1.

The still another invention with the above-mentioned structure andfunction provides the following effects.

It becomes possible and easier to access five surfaces other than thesupported surface among six surfaces of the movable block. Therefore,for example, in the case where a work as the movable block is fixed tothe reference block, the five surfaces can be continuously machined byone clamping operation. In the case where a work pallet as the movableblock is fixed to the reference block, available area of the work palletis significantly increased.

In the still another invention, it is preferable that, for example, asillustrated in FIG. 2A or FIG. 12A, the outer engaging member iscomposed of an annular outer sleeve 31. In this case, the outer engagingmember can be mechanically simple and compact in size.

The still another invention includes the following clamping apparatus.

For example, as illustrated in FIG. 7A or FIG. 17A, the outer engagingmember is composed of a plurality of pressing members 72 arrangedcircumferentially at intervals, and an annular plug 71 to be insertedinto the socket hole 3 is arranged on an outer periphery of the innerengaging member 21. Each of the pressing members 72 is supported on aperipheral wall 71 a of the annular plug 71 radially movably and ismovable radially inward by a restoring means 74. The output portion ofthe output member 36 is connected to either the annular plug 71 or theinner engaging member 21.

In this case, the pressing members can be significantly projected outdiametrically outward, by which the present invention becomes applicableeven when fitting gaps between outer peripheral surfaces of the pressingmembers and the socket hole are large.

In the respective invention described above, for example, as shown inFIG. 2A or FIG. 7A, it is preferable that the inner sleeve (or the innerengaging member) 21 is diametrically expandable and contractible. Inthis case, during the locking movement, the inner sleeve (or the innerengaging member) diametrically contracts when the outer sleeve (or theouter engaging member) gradually makes a wedge engagement with the innersleeve (or the inner engaging member), by which the inner peripheralsurface of the inner sleeve (or the inner engaging member) comes intoclose contact with an outer peripheral surface of the central pillar.Therefore, the movable member can be constrained on the reference blockvia the outer sleeve (or the outer engaging member), the inner sleeve(or the inner engaging member) and the central pillar in the recitedorder. Thereby, a clamping apparatus with a positioning function can beprovided.

The still another invention includes the following clamping apparatus.

For example, as shown in FIG. 2A or FIG. 7A, the outer engaging member31 (72) is advanced toward the leading end by an advancing means 25, andduring the locking movement, the outer engaging member 31 (72) movestoward the base end against the advancing means 25 while diametricallyexpanding.

According to this invention, the function of the advancing means makesit possible to drive the outer engaging member toward the base end afterthe outer engaging member has been diametrically expanded and has comeinto close contact with the socket hole, by which a strong locking forcecan be secured.

It is noted that, the advancing means 25 is only required to advance theouter engaging member 31 (72) toward the leading end, and it is possiblethat the advancing means 25 directly advances the outer engaging member31 (72) or indirectly advances the outer engaging member 31 (72) viaanother member such as the inner engaging member 21. In addition, theadvancing means 25 can employ an elastic material such as a spring orrubber, or such as a fluid pressure cylinder.

In addition, the still another invention includes the following clampingapparatus.

For example, as shown in FIG. 18A or FIG. 24, the inner engaging member21 is diametrically expandable and contractible, an annular clearance 92is formed between the central pillar 20 and the inner engaging member21, and during the locking movement, the outer engaging member (31, 72)diametrically contracts the inner engaging member 21, and the outerengaging member (31, 72) moves toward the base end while diametricallyexpanding.

According to this invention, since the inner engaging member has thefunction as the above-mentioned advancing means, an exclusive advancingmeans can be omitted, by which the clamping apparatus can bemechanically simple.

In the still another invention, for example, as shown in FIG. 2A or FIG.7A, it is preferable that the outer engaging member 31 (72) makes awedge engagement with the inner engaging member 21 from the leading endside. In this case, a strong locking force can be secured during thelocking movement.

In the still another invention, for example, as shown in FIG. 12A orFIG. 17A, the outer engaging member 31 (72) may make a wedge engagementwith the inner engaging member 21 from the base end side.

In the above-described respective invention, for example, as shown inFIG. 2A or FIG. 7A, it is preferable that substantially an entirecircumference of an inner peripheral surface of the inner sleeve (or theinner engaging member) 21 is adapted to come into close contact with anouter peripheral surface of the central pillar 20. In this case,positioning accuracy of the positioning function is further improved.

In the above-described respective invention, for example, as shown inFIG. 2A or FIG. 7A, it is preferable that at least one slit 22 isprovided in a peripheral wall of the inner sleeve (or the inner engagingmember) 21, and the inner sleeve (or the inner engaging member) 21 isdiametrically expandable by its own elastic restoring force. In thiscase, the inner sleeve (or the inner engaging member) can bemechanically simple and compact in size.

In the above-described respective invention, for example, as shown inFIG. 4, it is preferable that a pair of projecting portions 62, 62,which radially face each other, are provided on at least one of theouter periphery of the central pillar 20, the inner or outer peripheryof the inner engaging member 21 and the inner or outer periphery of theouter sleeve (or the outer engaging member) 31, and escape grooves 63,63 are formed between these projecting portions 62, 62. In this case, anaxial gap between the axis of the socket hole and the axis of thecentral pillar can be absorbed by these escape grooves.

In the respective invention, for example, as shown in FIG. 2A or FIG.7A, it is preferable that the central pillar 20 is fixed to thereference block 1.

In addition, for example, as shown in FIG. 5A and FIG. 5B, or, FIG. 15Aand FIG. 15B, it is preferable that the inner sleeve (or the innerengaging member) 21 is attached to at least one of the central pillar 20and the output member 36 radially movably. In this case, the axial gapbetween the axis of the socket hole and the axis of the central pillarcan be absorbed by a radial movement of the inner sleeve (or the innerengaging member) and a radial movement of the outer sleeve.

In the above-described respective invention, for example, as shown inFIG. 6 or FIG. 16, the central pillar 20 may be supported on thereference block 1 radially movably. In this case, the axial gap betweenthe axis of the socket hole and the axis of the central pillar can beabsorbed by a radial movement of the central pillar.

The above-described respective invention includes the following clampingapparatus.

For example, as shown in FIG. 25, in a state that the output member 36has moved toward the leading end for releasing, the movable block 2 isreceived by the reference block 1 via the output member 36, and aseating gap alpha is formed between the support surface 1 a of thereference block 1 and the supported surface 2 a of the movable block 2.

According to this invention, when the movable block is mounted to thereference block, the supported surface of the movable block can beprevented from colliding with the supporting surface of the referenceblock by the output member, whereby the supporting surface can beprevented from being damaged. Therefore, the positioning function of theclamping apparatus can be kept excellent for a long time.

A new clamping system of the present invention uses the above-describedclamping apparatus, and is composed as follows, for example, as shown inFIG. 1 through FIG. 4.

Two of the socket holes 3, 3 are provided in the movable block 2 at apredetermined interval. A first plug means 11 and a second plug means 12corresponding to the respective socket hole 3, 3 are provided in thereference block 1. Each of the plug means 11, 12 has the central pillar20, the inner sleeve (or the inner engaging member) 21 and the outersleeve 31. The first plug means 11 is composed so that substantially anentire circumference of an inner peripheral surface of the inner sleeve(or the inner engaging member) 21 is adapted to come into close contactwith an outer peripheral surface of the central pillar 20. The secondplug means 12 is provided with a pair of projecting portions 62, 62,which radially face each other, on at least one of the outer peripheryof the central pillar 20, the inner or outer periphery of the innersleeve (or the inner engaging member) 21 and the inner or outerperiphery of the outer sleeve 31, while escape grooves 63, 63 are formedbetween these projecting portions 62, 62. According to this invention,the movable block can be accurately positioned on and fixed to thereference block with a mechanically simple structure.

The invention of the clamping system includes the following structureshown in FIG. 1 and FIG. 7A for example.

Two of the socket holes 3, 3 are provided in the movable block 2 at apredetermined interval. A first plug means 11 and a second plug means 12corresponding to the respective socket hole 3, 3 are provided in thereference block 1. Each of the plug means 11, 12 has the central pillar20, the inner sleeve (or the inner engaging member) 21, the annular plug71 and a plurality of the pressing members 72. The first plug means 11is composed so that substantially an entire circumference of an innerperipheral surface of the inner sleeve (or the inner engaging member) 21is adapted to come into close contact with an outer peripheral surfaceof the central pillar 20, and three or more of the pressing members 72are arranged circumferentially at intervals. The second plug means 12 isprovided with two of the pressing members 72, which radially face eachother. According to this invention, the movable block can be accuratelypositioned on and fixed to the reference block with a mechanicallysimple structure.

In the above-described clamping system, for example, as shown in FIG. 1,FIG. 5A and FIG. 5B, it is preferable that at least one other sockethole 3 is provided in the movable block 2, and a third plug means 13only for locking corresponding to said other socket hole 3 is providedin the reference block 1. In this case, the movable block can bestrongly fixed to the reference block by the third plug means.

In addition, in the above-mentioned clamping system, for example, asshown in FIG. 1, FIG. 5A and FIG. 5B, the third plug means 13 has thecentral pillar 20, the inner sleeve (or the inner engaging member) 21and the outer sleeve 31, and the central pillar 20 is fixed to thereference block 1. It is preferable that the inner sleeve (or the innerengaging member) 21 is attached to at least one of the central pillar 20and the output member 36 radially movably. In this case, absorption ofan axial gap between the axis of the socket hole and the axis of thecentral pillar by a radial movement of the inner sleeve (or the innerengaging member) and a radial movement of the outer sleeve can beconsistent with security of a strong locking force.

For example, as shown in FIG. 1, FIG. 7A and FIG. 7B, it is preferablethat the third plug means 13 has the central pillar 20, the inner sleeve(or the inner engaging member) 21, the annular plug 71 and a pluralityof the pressing members 72, and the central pillar 20 is fixed to thereference block 1, and the inner sleeve (or the inner engaging member)21 is attached to the central pillar 20 radially movably. In this case,absorption of the axial gap between the axis of the socket hole and theaxis of the central pillar by the radial movement of the inner sleeve(or the inner engaging member) and the radial movement of the pressingmembers can be also consistent with security of the strong lockingforce.

In addition, for example, as shown in FIG. 1 and FIG. 6, the third plugmeans 13 may have the central pillar 20, the inner sleeve (or the innerengaging member) 21 and the outer sleeve 31, and the central pillar 20is supported on the reference block 1 radially movably. In this case,absorption of the axial gap between the axis of the socket hole and theaxis of the central pillar by a radial movement of the central pillarcan be consistent with security of the strong locking force.

Furthermore, the third plug means 13 may have the central pillar 20, theinner sleeve (or the inner engaging member) 21, the annular plug 71 anda plurality of the pressing members 72, and the central pillar 20 issupported on the reference block 1 radially movably. In this case,absorbing of the axial gap between the axis of the socket hole and theaxis of the central pillar can be also consistent with the security ofthe strong locking force.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 through FIG. 5B illustrate a first embodiment according to thepresent invention, wherein

FIG. 1 is a schematic view illustrating the principle of a clampingsystem using the present invention, and is a horizontal sectional viewof the clamping system;

FIG. 2A is an elevational sectional view of a released state of aclamping apparatus of the clamping system, corresponding to a viewindicated by the arrow 2A-2A in FIG. 1 or FIG. 2B;

FIG. 2B is a plan view of the clamping apparatus;

FIG. 3 is an enlarged sectional view indicated by the arrow 3-3 in FIG.2A, illustrating a positioning mechanism provided in the clampingapparatus;

FIG. 4 is a view similar to FIG. 3, illustrating another positioningmechanism provided in the clamping apparatus;

FIG. 5A and FIG. 5B illustrate another clamping apparatus of theclamping system, wherein

FIG. 5A is a partial view similar to FIG. 2A;

FIG. 5B is a view similar to FIG. 3;

FIG. 6 is a view similar to FIG. 5A, illustrating an exemplifiedvariation of the another clamping apparatus;

FIG. 7A through FIG. 8 illustrate a clamping apparatus of a secondembodiment according to the present invention, wherein

FIG. 7A is a view similar to FIG. 2A, corresponding to a view indicatedby the arrow 7A-7A in FIG. 7B;

FIG. 7B is a plan view of the clamping apparatus, similar to FIG. 2B;

FIG. 8 is an enlarged horizontal sectional view of a main portion inFIG. 7A, illustrating a restoring means of a pressing member;

FIG. 9 is a view similar to FIG. 8, illustrating an exemplifiedvariation of the restoring means;

FIG. 10 is a partial view similar to FIG. 2A, illustrating anexemplified variation of an advancing means provided in the varioustypes of clamping apparatuses;

FIG. 11 is a view similar to FIG. 2A, illustrating a clamping apparatusof a third embodiment according to the present invention;

FIG. 12A through FIG. 15B illustrate a clamping apparatus of a fourthembodiment according to the present invention, wherein

FIG. 12A is a view similar to FIG. 2A;

FIG. 12B is a view similar to FIG. 2B;

FIG. 13 is a view similar to FIG. 3, illustrating a positioningmechanism provided in the clamping apparatus;

FIG. 14 is a view similar to FIG. 4, illustrating another positioningmechanism provided in the clamping apparatus;

FIG. 15A and FIG. 15B illustrate another clamping apparatus of thefourth embodiment, wherein

FIG. 15A is a view similar to FIG. 5A;

FIG. 15B is a view similar to FIG. 5B;

FIG. 16 is a view similar to FIG. 6, illustrating an exemplifiedvariation of the another clamping apparatus;

FIG. 17A and FIG. 17B illustrate a clamping apparatus of a fifthembodiment according to the present invention, wherein

FIG. 17A is a view similar to FIG. 7A;

FIG. 17B is a view similar to FIG. 7B;

FIG. 18A through FIG. 21B illustrate a clamping apparatus of a sixthembodiment according to the present invention, wherein

FIG. 18A is a view similar to FIG. 2A;

FIG. 18B is a view similar to FIG. 2B;

FIG. 19A is a view similar to FIG. 3, illustrating a released state of apositioning mechanism provided in the clamping apparatus;

FIG. 19B is a view similar to FIG. 19A, illustrating a locked state ofthe positioning mechanism;

FIG. 20A is a view similar to FIG. 4, illustrating a released state ofanother positioning mechanism provided in the clamping apparatus;

FIG. 20B is a view similar to FIG. 20A, illustrating a locked state ofthe another positioning mechanism;

FIG. 21A and FIG. 21B illustrate another clamping apparatus of the sixthembodiment, wherein

FIG. 21A is a view similar to FIG. 5A;

FIG. 21 B is a view similar to FIG. 5B;

FIG. 22 is a view similar to FIG. 6, illustrating an exemplifiedvariation of the another clamping apparatus;

FIG. 23 is a partial view similar to FIG. 18A, illustrating a differentmode of the clamping apparatus of the sixth embodiment;

FIG. 24 is a partial view similar to FIG. 7A, illustrating a clampingapparatus of a seventh embodiment according to the present invention;and

FIG. 25 is a view similar to FIG. 2A, illustrating a clamping apparatusof an eighth embodiment according to the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1 through FIG. 5B show a first embodiment according to the presentinvention, illustrating a clamping apparatus of the present inventionapplied to a clamping system for a work pallet.

In this embodiment, as shown in FIG. 1 and FIG. 2A, a reference block 1is placed on a table T of a machine tool, and a supported surface 2 a ofthe work pallet 2 as a movable block is received by a supporting surface1 a of the reference block 1. In the supported surface 2 a are opened aplurality of socket holes 3 formed into circular straight holes. Herein,four of the socket holes 3 are illustrated.

The reference block 1 is provided with a base plate 4 fixed to the tableT. Corresponding to the socket holes 3, the base plate 4 is providedwith both a first plug means 11 and a second plug means 12, both ofwhich have both a positioning function and a locking function, and withtwo third plug means 13, 13, which have only a locking function. Thefirst plug means 11 and the second plug means 12 are arrangeddiagonally, and the two of the third plug means 13, 13 are also arrangeddiagonally.

As shown in FIG. 1, the first plug means 11 radially expands an outersleeve 31 described later by a wedge action to bring substantially anentire circumference of a peripheral wall of the outer sleeve 31 intoclose contact with the socket hole 3, and the first plug means 11positions the work pallet 2 on the reference block 1 in a horizontaldirection via the outer sleeve 31. Subsequently, the outer sleeve 31,which is in the close contact state with the socket hole 3, is drivendownward to fix the work pallet 2 to the reference block 1.

As shown in FIG. 1, the second plug means 12 is composed so as to applya diametrically expanding force to the outer sleeve 31 in two directionssubstantially orthogonal to a straight line L connecting both the axis Aand B of central pillars 20, 20 described later, and to bring two pointsin the circumferential direction of the outer sleeve 31 into closecontact with the socket hole 3, whereby the work pallet 2 is preventedfrom rotating around the axis A. Subsequently, the outer sleeve 31,which is in the close contact state with the socket hole 3, is drivendownward to fix the work pallet 2 to the reference block 1.

The third plug means 13 is formed so that the outer sleeve 31 isradially movable relative to the central pillar 20 described later, sothat the third plug means 13 does not have the positioning functionmentioned above.

The first plug means 11 and the second plug means 12 have the samestructure except for differences described later, and are basically thesame in the following structural points.

Into a installation hole 4 a of the base plate 4 is fitted a housing 15,and a flange 16 of the housing 15 is fixed to a peripheral wall of theinstallation hole 4 a by four fastening bolts 17. It is noted that thereference numeral 18 denotes a jack bolt. To extract the housing 15 fromthe installation hole 4 a, it is only required that the jack bolt 18 isscrewed downward and a lower end of the jack bolt 18 is pressed towardthe base plate 4.

The annular central pillar 20 is projected upward (toward a leading end)from the housing 15. The axis of the central pillar 20 substantiallycoincides with the axis of the installation hole 4 a. An upper surfaceof the flange 16 forms the above-mentioned supporting surface 1 a.

Onto an outer periphery of the central pillar 20 is fitted acollet-shaped inner sleeve (an inner engaging member) 21 verticallymovably within a predetermined range. Herein, one slit 22, whichvertically extends, is formed in a peripheral wall of the inner sleeve21, by which the inner sleeve 21 is diametrically expandable andcontractible, and the inner sleeve 21 is expanded diametrically andslightly by its own elastic restoring force. It is noted that a leadingend of a whirl-stop pin 23 fixed to the central pillar 20 is insertedinto the slit 22. It is preferable that a sealing member (not shown)made of rubber or the like is attached to the slit 22.

The inner sleeve 21 is urged upward by an advancing means composed ofone coned disc spring 25. An upper end of the inner sleeve 21 isreceived by a retaining ring 26 attached to an upper portion of thecentral pillar 20.

A tapered inner surface of the outer sleeve (an outer engaging member)31 to be inserted into the socket hole 3 makes a tapering engagement (awedge engagement) with a tapered outer surface of the inner sleeve 21from above. Both the tapered inner surface of the outer sleeve 31 andthe tapered outer surface of the inner sleeve 21 are formed in such amanner as to narrow upward. The outer sleeve 31 is formed into a colletshape like the inner sleeve 21. Namely, one slit 32, which verticallyextends, is formed in a peripheral wall of the outer sleeve 31, by whichthe outer sleeve 31 is diametrically expandable and contractible, andthe outer sleeve 31 is diametrically contracted by its own elasticrestoring force. It is noted that a leading end of a rotation stopperpin 33 fixed to the inner sleeve 21 is inserted into the slit 32. It ispreferable that a sealing member (not shown) made of rubber or the likeis attached to the slit 32.

Into the housing 15 is inserted an output member 36 vertically movably.The output member 36 is provided with a piston 38, which is hermeticallyinserted into a cylinder hole 37 at a lower portion of the housing 15, apiston rod 40, which projects upward from the piston 38 and ishermetically inserted into a rod hole 39, an output rod 41, whichprojects upward from the piston rod 40 and is inserted into acylindrical hole 20 a of the central pillar 20, a cap 43, which is fixedto an upper portion of the output rod 41 by a joint bolt 42, and a ring44, which is pressed to the upper portion of the output rod 41 by thecap 43.

Between a lower flange of the ring 44 and a lower surface of the cap 43is fitted an upper flange 45 of the outer sleeve 31 radially slidably.

With the above-described structure, an inner space of the outer sleeve31 can be covered with the cap 43 and the ring 44, by which foreignmatter such as swarf and cutting oil can be prevented from entering theinner space of the outer sleeve 31. In other words, both the cap 43 andthe lower flange of the ring 44 form a ceiling wall of the inner spaceof the outer sleeve 31.

In the housing 15 are provided a locking means 51 and a releasing means52, as a driving means D. The locking means 51 is composed of the piston38 and a lock chamber 53 formed above the piston 38. The lock chamber 53communicates with a supply and discharge port 54, which is forpressurized oil for locking. The releasing means 52 is composed of thepiston 38 and a release chamber 56 formed below the piston 38. Therelease chamber 56 communicates with a supply and discharge port 57,which is for pressurized oil for releasing.

In addition, the first plug means 11 is provided with a seatingconfirmation means. Namely, in the supporting surface 1 a is opened adetection nozzle hole 59, and into the detection nozzle hole 59 issupplied compressed air for detection. Then, when the supported surface2 a comes into contact with the supporting surface 1 a, the pressure inthe detection nozzle hole 59 increases. It can be confirmed that thework pallet 2 is seated on the housing 15 by detecting the increase ofthe pressure using a pressure switch, etc.

As shown in FIG. 3, a positioning mechanism 11 a of the first plug means11 is composed so that substantially an entire circumference of an innerperipheral surface of the inner sleeve 21 is adapted to come into closecontact with an outer peripheral surface of the central pillar 20.Therefore, the inner sleeve 21 is adapted to expand substantially anentire circumference of the peripheral wall of the outer sleeve 31radially outward (see FIG. 1).

The positioning mechanism 12 a of the second plug means 12 is differentfrom the positioning mechanism 11 a of the first plug means 11 in thefollowing structural points.

As shown in FIG. 4, a pair of projecting portions 62, 62, which radiallyface each other, are provided on the outer periphery of the centralpillar 20, and escape grooves 63, 63 are formed between these projectingportions 62, 62. Thereby, the projecting portions 62, 62 generate adiametrically expanding force at two points, which radially face eachother, on the peripheral wall of the outer sleeve 31 via the innersleeve 21 (see FIG. 1).

Instead of or in addition to projecting the projecting portions 62, 62from the central pillar 20, the projecting portions 62, 62 may beprojected inward from an inner peripheral surface of the outer sleeve 31or may be projected outward from an outer peripheral surface of theouter sleeve 31. Furthermore, the projecting portions 62, 62 may beprojected inward from the inner peripheral surface of the inner sleeve21 or may be projected outward from an outer peripheral surface of theinner sleeve 21.

The third plug means 13 is different from the first plug means 11 in thefollowing structural points as shown in FIG. 5A and FIG. 5B. FIG. 5A andFIG. 5B are similar to FIG. 2A and FIG. 3, respectively.

The peripheral wall of the inner sleeve 21 is formed in acircumferentially seamless manner without any slit. The inner sleeve 21is fitted onto the central pillar 20 radially movably with a radialclearance 65 spaced. As described above, between the cap 43 and the ring44 is supported the outer sleeve 31 radially movably. Thereby, the innersleeve 21 and the outer sleeve 31 are allowed to move radially relativeto the central pillar 20, by which an axial gap between the axis of thesocket hole 3 and the axis of the central pillar 20 can be canceled.

The first plug means 11, the second plug means 12 and the third plugmeans 13 operates in almost the same manner as follows.

In a released state shown in FIG. 2A, pressurized oil in the lockchamber 53 has been discharged and pressurized oil has been supplied tothe release chamber 56. Thereby, the piston 38 has made the output rod41 ascend, and the output rod 41 has made the outer sleeve 31 ascend viathe cap (an output portion) 43 and the ring 44, and the outer sleeve 31has been switched into a diametrically contracted state. The innersleeve 21 has ascended by an advancing stroke by the coned disc spring25, and has made a slight tapering engagement with the outer sleeve 31or has been facing the outer sleeve 31 with a slight gap spacedtherebetween.

To position the work pallet 2 on the reference block 1, first, as shownin FIG. 1 and FIG. 2A, the work pallet 2 is made to descend with theplug means 11, 12, 13 being in the above-mentioned released state to fitthe socket hole 3 onto the outer sleeve 31.

Next, the pressurized oil in the release chamber 56 is discharged andpressurized oil is supplied to the lock chamber 53. Then, the piston 38makes the outer sleeve 31 descend via the output rod 41 and the cap (theoutput portion) 43, and the tapered inner surface of the outer sleeve 31gradually makes a wedge engagement with the tapered outer surface of theinner sleeve 21.

Then, the outer sleeve 31 diametrically expands via the inner sleeve 21held at almost a raised position by an urging force of the coned discspring 25, and the outer sleeve 31 comes into contact with the sockethole 3. Next, the outer sleeve 31 diametrically expands whilecompressing the coned disc spring 25 downward via the inner sleeve 21,and the outer sleeve 31 comes into close contact with the socket hole 3,and the outer sleeve 31 positions the work pallet 2 in the horizontaldirection via the diametrically contracted inner sleeve 21 and via thecentral pillar 20, and simultaneously, the outer sleeve 31 forces theinner sleeve 21 to retreat gradually downward against the urging forceof the coned disc spring 25. Subsequently, when the inner sleeve 21descends by a dimension corresponding to the advancing stroke with theconed disc spring 25 being fully compressed, the inner sleeve 21 isreceived by the housing 15 via the coned disc spring 25. Then, the outersleeve 31 makes a strong wedge engagement with the inner sleeve 21,which is received by the housing, to expand diametrically, by which theouter sleeve 31 comes into strong and close contact with the socket hole3. Thereby, the output member 36 strongly presses the supported surface2 a of the work pallet 2 toward the supporting surface 1 a of thereference block 1 via the outer sleeve 31, which is in the strong andclose contact state with the socket hole 3.

It is noted that, in the case where the supporting surface la and thesupported surface 2 a are in almost complete contact with each other atthe beginning of the locking movement and where the supported surface 2a is received by the supporting surface 1 a, the outer sleeve 31operates as follows during the locking movement.

After the outer sleeve 31 comes into close contact with the socket hole3, the outer sleeve 31 descends downward while sliding on the sockethole 3. Then, as mentioned above, when the inner sleeve 21 makes theconed disc spring 25 be in the fully compressed state, the outer sleeve31 comes into strong and close contact with the socket hole 3, and theouter sleeve 31 strongly presses the movable block 2 to the referenceblock 1.

On the other hand, in the case where a gap remains between thesupporting surface 1 a and the supported surface 2 a at the beginning ofthe locking movement for some reason, the outer sleeve 31 operates asfollows during the locking movement.

After the outer sleeve 31 comes into close contact with the socket hole3, the outer sleeve 31, which is in the close contact state with thesocket hole 3, pulls the movable block 2 downward via the socket hole 3.Then, as mentioned above, when the inner sleeve 21 makes the coned discspring 25 be in the fully compressed state, the outer sleeve 31 comesinto strong and close contact with the socket hole 3, and the outersleeve 31 strongly presses the movable block 2 to the reference block 1.

Simultaneously with those operations of the first plug means 11 and thesecond plug means 12, the two third plug means 13, 13, which have onlythe locking function, strongly fix the work pallet 2 to the referenceblock 1 via the outer sleeve 31.

When switching from the locked state to the released state, as describedabove, it is only required to discharge the pressurized oil in the lockchamber 53 and to supply pressurized oil to the release chamber.Thereby, the piston 38 makes the outer sleeve 31 ascend via the outputrod 41, and the outer sleeve 31 diametrically contracts by its ownelastic restoring force, by which the locked state is canceled.

It is noted that the third plug means 13 may employ a structure shown inan exemplified variation illustrated in FIG. 6, in place of the axialgap absorption structure shown in FIG. 5A and FIG. 5B.

FIG. 6 is a view similar to FIG. 5A, wherein the central pillar 20 issupported on the housing 15 radially movably. In detail, between anouter peripheral surface of the output rod 41 and the cylindrical hole20 a of the central pillar 20 is formed a first radial clearance 66, andbetween the outer peripheral surface of the central pillar 20 and thehousing 15 is formed a second radial clearance 67.

The first embodiment and the exemplified variation can be changed asfollows.

An outer surface of the outer sleeve 31 may be formed in a serrated orirregular manner instead of being formed in a vertically straightmanner.

The inner sleeve 21 and the outer sleeve 31, which are diametricallyexpandable and contractible, may be provided with a plurality of throughgrooves opened in the respective annular wall thereof in such a mannerthat the through grooves are opened alternately in an upper and lowersurface, instead of being provided with a slit 22, 32 in the respectiveannular wall. It is also possible that each of the sleeves 21, 31 iscomposed of a plurality of divided members arranged circumferentially.

The outer surface of the inner sleeve 21 may be composed of a pluralityof inclined wedge surfaces arranged circumferentially at predeterminedintervals, instead of the tapered surface presented as an example. Inthis case, a plurality of inclined grooves may be arrangedcircumferentially at predetermined intervals on the outer surface of theinner sleeve 21, and the bottom walls of the inclined grooves form theinclined wedge surfaces. In addition, the inner surface of the outersleeve 31 may be also composed of a plurality of inclined wedge surfacesarranged circumferentially at predetermined intervals, instead of thetapered surface presented as an example.

The inner sleeve 21 and the outer sleeve 31 may make an indirectengagement with each other via another member, instead of making adirect engagement.

It is noted that, it is preferable that each of the plug means 11, 12,13 are provided with a cleaning means to clean the contact portionbetween the supporting surface la and the supported surface 2 a, theengaged portion between the socket hole 3 and the outer sleeve 31, andthe engaged surface between the outer sleeve 31 and the inner sleeve 21and the like, using pressurized fluid such as compressed air.

In addition, in regard to the second plug means 12 shown in FIG. 4 andthe third plug means 13 shown in FIG. 5A and FIG. 5B (or FIG. 6), it ispreferable that the coned disk spring 25 is arranged in such a mannerthat, at the beginning of the locking movement, the urging force of theconed disc spring 25, which acts relative to the inner sleeve 21, is setweak or is set in such a manner that the urging force does not act atall relative to the inner sleeve 21, at the middle of the lockingmovement, the urging force gradually acts relative to the inner sleeve21. Thereby, when the axial gap between the axis of the socket hole 3and the axis of the central pillar 20 is absorbed, a radial frictionalforce, which acts relative to the inner sleeve 21 (or the radiallymovable central pillar 20 and the inner sleeve 21, both shown in FIG.6), remains weak, by which both the inner sleeve 21 and the outer sleeve31 can radially move smoothly.

FIG. 7A through FIG. 25 show a plurality of embodiments and exemplifiedvariations relating to the present invention. In these otherembodiments, components similar to those of the first embodiment will bedesignated and described by the same numerals as a general rule.

FIG. 7A and FIG. 7B, and FIG. 8 show a first plug means (a clampingapparatus) 11 of a second embodiment according to the present invention.FIG. 7A is a view similar to FIG. 2A, corresponding to a view indicatedby the arrow 7A-7A in FIG. 7B. FIG. 7B is a plan view of the first plugmeans 11, similar to FIG. 2B. FIG. 8 is an enlarged horizontal sectionalview of a main portion in FIG. 7A.

The first plug means 11 of the second embodiment is different from thefirst embodiment in the following points.

In place of the outer sleeve 31, which is diametrically expandable andcontractible as shown in FIG. 2A, an annular plug 71 to be inserted intothe socket hole 3 is arranged on an outer periphery of the inner sleeve21. A peripheral wall 71 a of the annular plug 71 is formed in acircumferentially seamless manner without any slit. Three pressingmembers 72 are supported on the peripheral wall 71 a of the annular plug71 and arranged circumferentially at intervals. An inner surface of eachof the pressing members 72 makes a wedge engagement with the outersurface of the inner sleeve 21 from above. Each of the pressing members72 is movable radially inward by a restoring means 74 (see FIG. 8). Anupper end portion (a leading end portion) of the output member 36 isfixed to the annular plug 71 via the cap 43.

It is noted that the output member 36 is blocked from rotating by a pin73 inserted into the piston 38.

The restoring means 74 shown in FIG. 8 is composed of a rod-shapedspring fitted between the annular plug 71 and a through hole 72 a ofeach of the pressing members 72. The spring restoring means 74 urges thepressing members 72 toward the outer peripheral surface of the innersleeve 21.

FIG. 9 is a view similar to FIG. 8, showing an exemplified variation ofthe restoring means 74.

In this case, on the outer peripheral surface of the inner sleeve 21 areprovided a plurality of inclined grooves 75 circumferentially atintervals, and each of the inclined grooves 75 are formed into a T shapein a plan view, the restoring means 74 is formed by a fitting structurebetween both side walls of each of the inclined grooves 75 and an innerend portion of each of the pressing members 72. On a bottom wall of eachof the inclined groove 75 is formed a wedge surface 76.

It is noted that each of the inclined grooves 75 may be formed into a Vshape or the like in the plan view, instead of being formed into the Tshape as mentioned above.

Differences between the operation of the second embodiment and theoperation of the first embodiment is that, during the locking operation,each of the pressing members 72 supported on the annular plug 71 areprojected out radially outward, and an outer surface of each of thepressing member 72 comes into strong and close contact with the sockethole 3.

Each of the pressing members 72 may make an indirect engagement with theouter surface of the inner sleeve 21 via another member, instead ofmaking a direct engagement. The number of the pressing members 72provided may be two or four or more, instead of being three presented asan example.

In addition, the outer surface of each of the pressing members 72 may beformed into a serrated or irregular manner, instead of being formed intoa vertically straight manner.

It is preferable that a supply port for a cleaning fluid is provided inthe reference block 1, and discharge ports for the cleaning fluid isformed by a fitting gap between the peripheral wall 71 a of the annularplug 71 and the pressing members 72, and that the discharge portcommunicates with the supply port. In this case, the fitting gap can beautomatically cleaned, by which the pressing members 72 move with highaccuracy and smoothly.

The advancing means may be a plurality of coned disc springs laminatedvertically or may be a compression coil spring, rubber and the like,instead of the one coned disc spring 25 presented as an example.

In addition, it is sufficient that the advancing means has a functionthat can press the outer sleeve 31 upward with a predetermined force,that is, the advancing means can employ a cylindrical structure usingpressurized fluid such as pressurized oil and compressed air as shown inthe exemplified variation shown in FIG. 10 for example, instead of (orin addition to) employing an elastic member such as the spring 25.

FIG. 10 is a partial view similar to FIG. 2A. In this case, an annularadvancing piston 78 is fitted onto an outer periphery of the piston rod40 of the output member 36, and a pressure receiving area of theadvancing piston 78 is set to a value smaller than a pressure receivingarea of the piston 38. And the pressure of the pressurized oil suppliedto the lock chamber 53 is adapted to press the outer sleeve 31 upwardvia the advancing piston 78, a plurality of connecting rods 79 (only oneconnecting rod is illustrated herein) and the inner sleeve 21 in therecited order.

FIG. 11 is a view similar to FIG. 2A, showing a first plug means 11 of athird embodiment according to the present invention.

In this case, the driving means D employs a human-powered type. Indetail, the output member 36 is provided with a bolt 82 screwed in ascrew hole 81 of the central pillar 20. During the locking operation, ahexagonal wrench 84 is inserted into an input hole (an input portion) 83at a head portion of the bolt 82, and the bolt 82 is rotated clockwisein a plan view. Then, the head portion of the bolt 82 makes the outersleeve 31 descend via the cap (the output portion) 43 with the outersleeve 31 diametrically expanded.

It is noted that the coned disc spring (the advancing means) 25 isprevented from being compressed more than a predetermined amount by anannular projection 85 provided around a lower portion of the centralpillar 20. It is preferable that this kind of projection 85 is alsoprovided in the above-described respective embodiment and respectiveembodiment described later.

FIG. 12A and FIG. 12B, and FIG. 13 show a first plug means 11 of afourth embodiment according to the present invention. FIG. 12A is a viewsimilar to FIG. 2A. FIG. 12B is a view similar to FIG. 2B. FIG. 13 is aview similar to FIG. 3, showing the positioning mechanism 11 a.

In this case, between the cap 43 and the ring 44 is supported an upperportion of the inner sleeve 21 radially movably, and the outer sleeve 31makes a wedge engagement with the inner sleeve 21 from below, and theouter sleeve 31 is urged upward by a plurality of the coned disc springs25. The outer sleeve 31 is blocked from moving upward by more than apredetermined amount by an annular holding wall 87.

It is noted that FIG. 14 is a view similar to FIG. 4, showing anotherpositioning mechanism 12 a.

FIG. 15A and FIG. 15B show a third plug means 13 of the fourthembodiment. FIG. 15A is a view similar to FIG. 5A, and FIG. 15B is aview similar to FIG. 5B.

In this case, the peripheral wall of the inner sleeve 21 is formed in acircumferentially seamless manner without any slit. The inner sleeve 21is fitted onto the central pillar 20 with a radial clearance 65 spacedradially movably, and on the cap 43 is supported an upper portion of theinner sleeve 21 radially movably. In addition, a lower portion of theouter sleeve 31 is supported on the housing 15 radially movably.Thereby, the inner sleeve 21 and the outer sleeve 31 are allowed to moveradially relative to the central pillar 20, by which the axial gapbetween the axis of the socket hole 3 and the axis of the central pillar20 can be absorbed.

FIG. 16 is similar to FIG. 6, showing an exemplified variation of thethird plug means 13.

In the exemplified variation shown in FIG. 16, the central pillar 20 issupported on the housing 15 radially movably. In detail, a first radialclearance 66 is formed between the outer peripheral surface of theoutput rod 41 and the cylindrical hole of the central pillar 20, and asecond radial clearance 67 is formed between the outer peripheralsurface of the central pillar 20 and the housing 15, and a third radialclearance 90 is formed between the lower portion of the outer sleeve 31and the housing 15.

FIG. 17A and FIG. 17B show a first plug means 11 of a fifth embodimentaccording to the present invention. FIG. 17A is a view similar to FIG.7A. FIG. 17B is a view similar to FIG. 7B.

In this case, the upper portion of the inner sleeve 21 is supported onthe cap 43 radially movably, and the annular plug 71 is arranged on theouter periphery of the inner sleeve 21. The annular plug 71 is urgedupward by a plurality of the coned disc springs 25, and a plurality ofthe pressing members 72 supported on the annular plug 71 make a wedgeengagement with the inner sleeve 21 from below.

FIG. 18A through FIG. 19B show a first plug means 11 of a sixthembodiment according to the present invention. FIG. 18A is a viewsimilar to FIG. 2A. FIG. 18B is a view similar to FIG. 2B. FIG. 19A is aview similar to FIG. 3, showing a released state of a positioningmechanism 11 a. FIG. 19B is a view similar to FIG. 19A, showing a lockedstate of the mechanism 11 a.

In the sixth embodiment, the slit 22 is provided in the peripheral wallof the inner sleeve 21, by which the inner sleeve 21 is diametricallyexpandable and contractible, and between the central pillar 20 and theinner sleeve 21 is formed a comparatively large annular clearance 92. Inthe released state, as shown in FIG. 19A, the inner sleeve 21 is kept ina slightly diametrically expanded state. Then, during the lockingmovement, as shown in FIG. 19B, the outer sleeve 31 diametricallycontracts the inner sleeve 21, and simultaneously, the outer sleeve 31descends while diametrically expanding.

It is noted that an elastic resistant force that occurs when the innersleeve 21 is diametrically contracted corresponds to the urging force ofthe coned disc spring (the advancing means).

FIG. 20A and FIG. 20B show another positioning mechanism 12 a. FIG. 20Ais a view similar to FIG. 4, showing a released state. FIG. 20B is aview similar to FIG. 20A, showing a locked state. The anotherpositioning mechanism 12 a is different from the positioning mechanism 1la in that the projecting portions 62, 62 and escape grooves 63, 63 areprovided on the outer peripheral surface of the central pillar 20.

FIG. 21A and FIG. 21B show a third plug means 13 of the sixthembodiment. FIG. 21A is a view similar to FIG. 5A. FIG. 21 B is a viewsimilar to FIG. 5B.

In this case, to the outer periphery of the central pillar 20 isinserted an intermediate sleeve 94 radially movably, and to an outerperiphery of the intermediate sleeve 94 is inserted the inner sleeve 21with the annular clearance 92 spaced, and the outer sleeve 31 makes awedge engagement with the inner sleeve 21 from above.

FIG. 22 is a view similar to FIG. 6, showing an exemplified variation ofthe third plug means 13. The structure of this exemplified variation isdifferent from the structure shown in FIG. 6 in that, between thecentral pillar 20 that is radially movable and the inner sleeve 21 isprovided a comparatively large annular clearance 92, and the coned discspring (the advancing means) 25 shown in FIG. 6 is omitted.

FIG. 23 is a partial view similar to FIG. 18A, showing a different modeof the first plug means 11 of the sixth embodiment.

In this case, a resistant means 96 made of a rubber ring is attached tothe inner periphery of the inner sleeve 21. This resistant means 96 isadapted to increase a resistant force that occurs when the inner sleeve21 is diametrically contracted.

It is noted that the resistant means 96 can be made of plastic or metal,instead of being made of rubber presented as an example. In addition,the resistant means 96 may be attached to the outer periphery of thecentral pillar 20, instead of (or in addition to) being attached to theinner periphery of the inner sleeve 21.

In addition, a protection sleeve 97 is attached to an upper half of theouter sleeve 31 radially movably. The protection sleeve 97 covers anupper half of the slit 32, by which foreign matter such as swarf can besignificantly prevented from entering the slit 32. It is a matter ofcourse that the protection sleeve 97 is applicable to theabove-described respective clamping apparatuses.

FIG. 24 is a partial view similar to FIG. 7A, showing a first plug means11 of a seventh embodiment according to the present invention.

The structure of the seventh embodiment is different from the structureshown in FIG. 7A in that the annular clearance 92 is provided betweenthe central pillar 20 and the inner sleeve 21, and that the coned discspring (the advancing means) 25 shown in FIG. 7A is omitted.

FIG. 25 is a view similar to FIG. 2A, showing a clamping apparatus of aneighth embodiment according to the present invention. The structure ofthe eighth embodiment is different from the structure shown in FIG. 2Aas follows.

In the illustrated state that the output member 36 has been moved upwardfor releasing, the work pallet 2 is received by the reference block 1via at least one of the cap 43 and the connecting bolt 42 and via theoutput member 36, in the recited order. In the received state, a seatinggap alpha is formed between the supporting surface 1 a of the referenceblock 1 and the supported surface 2 a of the work pallet 2.

The above-described receiving structure exhibits the followingadvantages. When the work pallet 2 is mounted to the reference block 1,the supported surface 2 a of the work pallet 2 can be prevented fromcolliding with the supporting surface la of the reference block 1 by theoutput member 36. Thereby, the supporting surface 1 a can be preventedfrom being damaged. Therefore, the positioning function of the clampingapparatus can be kept excellent for a long time.

The receiving structure is applicable to the above-described respectiveembodiments and exemplified variations.

The above-described respective embodiments and respective exemplifiedvariations can be further changed as follows.

With respect to the clamping system, the exemplified number of thirdplug means 13 having only the locking function is two, but alternativelya single third means 13 or three or more third means 13 may be provided.The structure of the third plug means 13 is not limited to the structurepresented as an example, and the third plug means 13 may employ othertypes of clamps.

The exemplified driving method of the plug means 11, 12, 13 is thehydraulic double-acting one, but alternatively a spring-locking andhydraulic-releasing one or a hydraulic-locking and spring-releasing onemay also be employed.

The pressurized fluid to be used for locking or releasing may employgases such as compressed air, instead of employing the pressurized oilpresented as an example. In addition, the cleaning pressurized fluid mayemploy gases such as nitrogen or liquid, instead of employing thecompressed air.

In the case that the lowering force of the outer sleeve 31 or thepressing members 72 during the locking operation is set to asufficiently large value, the third plug means 13 can be omitted.

With respect to this clamping system, it is also possible to provide aplurality of first plug means 11 and a plurality of second plug means12. Furthermore, it is also possible that a plurality of the first plugmeans 11 are provided while the second plug means 12 is not provided, orthat a plurality of the second plug means 12 are provided while thefirst plug means 11 is not provided.

It is possible that a plurality of the plug means are arrangedcircumferentially or linearly.

The supporting surface la may be provided on the base plate 4 instead ofbeing provided on the upper surface of the flange 16 of the housing 15.

The central pillar 20 and the housing 15 may be formed separatelyinstead of being formed integrally. In this case, the central pillar 20is firmly fixed to the housing 15 by fastening with a bolt or bytightening with a screw.

In addition, the housing 15 and the base plate 4 may be formedintegrally instead of being formed separately.

The combination of the reference block and the movable block may be acombination of a table of a machine tool and a work pallet, acombination of a work pallet and a jig base, a combination of a jig baseand a work piece, or a combination of a working jig such as a weldingjig and an article such as a work piece instead of the combination ofthe base plate 4 and the work pallet 2 presented as an example. Inaddition, the present invention is also applicable to positioning of aworkpiece or tool, etc., of various kinds of processing machines such aslaser processing machines and electric discharge processing machines.

Besides, it is a matter of course that the clamping apparatus of thepresent invention can be used alone, instead of using a plurality of theclamping apparatuses at the same time.

1. A clamping apparatus, wherein An annular central pillar (20) is projected from a reference block (1) toward a leading end, an inner sleeve (21) is fitted onto the central pillar (20) axially movably within a predetermined range, and the inner sleeve (21) is advanced toward the leading end by a predetermined advancing stroke by an advancing means (25), an outer sleeve (31) to be inserted into a socket hole (3) of a movable block (2) makes a wedge engagement with the inner sleeve (21) from the leading end side, and the outer sleeve (31) is adapted to be diametrically expandable and contractible, an output member (36) is inserted into a cylindrical hole (20 a) of the annular central pillar (20) axially movably, and a leading end portion of the output member (36) is connected to the outer sleeve (31), a locking means (51) and a releasing means (52) are provided in the reference block (1), the locking means (51) moves the outer sleeve (31) toward a base end for locking via the output member (36), while the releasing means (52) moves the outer sleeve (31) toward the leading end for releasing via the output member (36).
 2. The clamping apparatus as set forth in claim 1, wherein in place of the outer sleeve (31), which is diametrically expandable and contractible, an annular plug (71) to be inserted into the socket hole (3) is arranged on an outer periphery of the inner sleeve (21), a plurality of pressing members (72) are supported on a peripheral wall (71 a) of the annular plug (71) radially movably and are arranged circumferentially at intervals, each of the pressing members (72) makes a wedge engagement with the inner sleeve (21) from the leading end side, and each of the pressing members (72) is movable radially inward by a restoring means (74), the leading end portion of the output member (36) is connected to the annular plug (71).
 3. A clamping apparatus, wherein an annular central pillar (20) is projected from a reference block (1) toward a leading end, an inner engaging member (21) is arranged on an outer periphery of the central pillar (20), an outer engaging member (31, 72) to be inserted into a socket hole (3) of a movable block (2) is diametrically expandable and contractible, the outer engaging member (31, 72) makes a wedge engagement axially with the inner engaging member (21), and the outer engaging member (31, 72), which is in the wedge engaged state, is movable toward a base end and diametrically expandable for locking, an output member (36) is inserted into the annular central pillar (20) axially movably, and an output portion of the output member (36) is connected to either the outer engaging member (31, 72) or the inner engaging member (21), an input portion of the output member (36) is connectable to a driving means (D).
 4. The clamping apparatus as set forth in claim 3, wherein the outer engaging member is composed of an annular outer sleeve (31).
 5. The clamping apparatus as set forth in claim 3, wherein the outer engaging member is composed of a plurality of pressing members (72) arranged circumferentially at intervals, an annular plug (71) to be inserted into the socket hole (3) is arranged on an outer periphery of the inner engaging member (21), each of the pressing members (72) is supported on a peripheral wall (71 a) of the annular plug (71) radially movably and is movable radially inward by a restoring means (74), the output portion of the output member (36) is connected to either the annular plug (71) or the inner engaging member (21).
 6. The clamping apparatus as set forth in claim 3, wherein the inner engaging member (21) is diametrically expandable and contractible.
 7. The clamping apparatus as set forth in claim 3, wherein the outer engaging member (31, 72) is advanced toward the leading end by an advancing means (25), and during the locking movement, the outer engaging member (31, 72) moves toward the base end against the advancing means (25) while diametrically expanding.
 8. The clamping apparatus as set forth in claim 3, wherein the inner engaging member (21) is diametrically expandable and contractible, an annular clearance (92) is formed between the central pillar (20) and the inner engaging member (21), and during the locking movement, the outer engaging member (31, 72) diametrically contracts the inner engaging member (21), and the outer engaging member (31, 72) moves toward the base end while diametrically expanding.
 9. The clamping apparatus as set forth in claim 3, wherein the outer engaging member (31, 72) makes a wedge engagement with the inner engaging member (21) from the leading end side.
 10. The clamping apparatus as set forth in claim 3, wherein the outer engaging member (31, 72) makes a wedge engagement with the inner engaging member (21) from the base end side.
 11. The clamping apparatus as set forth in claim 3, wherein substantially an entire circumference of an inner peripheral surface of the engaging member (21) is adapted to come into close contact with an outer peripheral surface of the central pillar (20).
 12. The clamping apparatus as set forth in claim 3, wherein at least one slit (22) is provided in a peripheral wall of the inner engaging member (21), and the inner engaging member (21) is diametrically expandable by its own elastic restoring force.
 13. The clamping apparatus as set forth in claim 3, wherein a pair of projecting portions (62) (62), which radially face each other, are provided on at least one of the outer periphery of the central pillar (20), an inner or outer periphery of the inner engaging member (21) and an inner or outer periphery of the outer engaging member (31), while escape grooves (63) (63) are formed between these projecting portions (62) (62).
 14. The clamping apparatus as set forth in claim 3, wherein the central pillar (20) is fixed to the reference block (1).
 15. The clamping apparatus as set forth in claim 4, wherein the inner engaging member (21) is attached to at least one of the central pillar (20) and the output member (36) radially movably.
 16. The clamping apparatus as set forth in claim 3, wherein the central pillar (20) is supported on the reference block (1) radially movably.
 17. The clamping apparatus as set forth in claim 1 or 3, wherein in a state that the output member (36) has moved toward the leading end for releasing, the movable block (2) is received by the reference block (1) via the output member (36), and a seating gap (alpha) is formed between a support surface (1 a) of the reference block (1) and a supported surface (2 a) of the movable block (2).
 18. A clamping system using the clamping apparatus as set forth in claim 1 or 4, wherein two of the socket holes (3) (3) are provided in the movable block (2) at a predetermined interval, a first plug means (11) and a second plug means (12) corresponding to the respective socket hole (3) (3) are provided in the reference block (1), each of the plug means (11) (12) has the central pillar (20), the inner sleeve or the inner engaging member (21) and the outer sleeve (31), the first plug means (11) is composed so that substantially an entire circumference of an inner peripheral surface of the inner sleeve or substantially an entire circumference of an inner peripheral surface of the inner engaging member (21) is adapted to come into close contact with an outer peripheral surface of the central pillar (20), the second plug means (12) is provided with a pair of projecting portions (62) (62), which radially face each other, on at least one of an outer periphery of the central pillar (20), an inner or outer periphery of the inner sleeve or the inner engaging member (21) and an inner or outer periphery of the outer sleeve (31), while escape grooves (63) (63) are formed between these projecting portions (62) (62).
 19. A clamping system using the clamping apparatus as set forth in claim 2 or 5, wherein two of the socket holes (3) (3) are provided in the movable block (2) at a predetermined interval, a first plug means (11) and a second plug means (12) corresponding to the respective socket hole (3) (3) are provided in the reference block (1), each of the plug means (11) (12) has the central pillar (20), the inner sleeve or the inner engaging member (21), the annular plug (71) and a plurality of the pressing members (72), the first plug means (11) is composed so that substantially an entire circumference of an inner peripheral surface of the inner sleeve or substantially an entire circumference of an inner peripheral surface of the inner engaging member (21) is adapted to come into close contact with an outer peripheral surface of the central pillar (20), and three or more of the pressing members (72) are arranged circumferentially at intervals, the second plug means (12) is provided with two of the pressing members (72), which radially face each other.
 20. The clamping system as set forth in claim 18, wherein at least one other socket hole (3) is provided in the movable block (2), a third plug means (13) only for locking corresponding to said other socket hole (3) is provided in the reference block (1).
 21. The clamping system as set forth in claim 19, wherein at least one other socket hole (3) is provided in the movable block (2), a third plug means (13) only for locking corresponding to said other socket hole (3) is provided in the reference block (1).
 22. The clamping system as set forth in claim 20, wherein the third plug means (13) has the central pillar (20), the inner sleeve or the inner engaging member (21), and the outer sleeve (31), the central pillar (20) is fixed to the reference block (1), the inner sleeve or the inner engaging member (21) is attached to at least one of the central pillar (20) and the output member (36) radially movably.
 23. The clamping system as set forth in claim 21, wherein the third plug means (13) has the central pillar (20), the inner sleeve or the inner engaging member (21), the annular plug (71) and a plurality of the pressing members (72), and the central pillar (20) is fixed to the reference block (1), and the inner sleeve or the inner engaging member (21) is attached to the central pillar (20) radially movably.
 24. The clamping system as set forth in claim 20, wherein the third plug means (13) has the central pillar (20), the inner sleeve or inner engaging member (21), and the outer sleeve (31), and the central pillar (20) is supported on the reference block (1) radially movably.
 25. The clamping system as set forth in claim 21, wherein the third plug means (13) has the central pillar (20), the inner sleeve or the inner engaging member (21), the annular plug (71) and a plurality of the pressing members (72), and the central pillar (20) is supported on the reference block (1) radially movably. 